Question about quantum of excitations in QED

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Discussion Overview

The discussion revolves around the nature of photons in quantum electrodynamics (QED), specifically focusing on the concepts of excitation modes of the electromagnetic field and the energy differences between these modes. The scope includes theoretical aspects of quantum field theory and the quantization of fields.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • Some participants express confusion regarding the distinction between "the excitation modes of the EM field" and "the energy difference between these excitation modes."
  • One participant suggests that there may be many excitation modes, with different modes corresponding to different energies.
  • A later reply questions whether every photon corresponds to a single excitation mode.
  • Another participant clarifies that photons are the quantization of the modes of the electromagnetic field.
  • It is noted that the quantized modes of the free electromagnetic field in vacuum are related to the eigenstates of the number operator.

Areas of Agreement / Disagreement

The discussion includes multiple viewpoints regarding the relationship between excitation modes and photons, and it remains unresolved whether there is a clear consensus on the nature of these concepts.

Contextual Notes

Participants express uncertainty about the definitions and relationships between excitation modes and energy differences, indicating potential limitations in their understanding.

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About photons, in qed, I have not understood if there is difference between "the excitation modes of the EM field" or "the energy difference between these excitation modes". Sorry if I make a mess with these concepts.

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There may be many excitation modes; the different modes represent different energies.
 
UltrafastPED said:
There may be many excitation modes; the different modes represent different energies.

So every photon is a single excitation mode or what?

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Photons are the quantization of the modes of the electromagnetic field.
 
The quantized modes of the free e-m field (in vacuum) are 1-1 related to the eigenstates of the number operator.
 
Thanks to both for the answeres.

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